Russian scientists are "very, very close" to reaching the surface of a freshwater lake 2.3 miles (3,768) meters under the Antarctic ice, news reports say. It would be the first time anyone has penetrated a subglacial lake on the frozen continent.

However Mahlon C. Kennicutt II, a professor of oceanography at Texas A&M University who leads several Antarctic research groups, said the report should be viewed with skepticism until an official announcement is made.

"I would be surprised if it was announced officially this quiet. Also, the one source [in the article] is unnamed, so it is hard to tell," he said.

Montana State ecologist John Priscu echoed Kennicutt's caution. "There are a lot of rumors going around about penetrating the lake, and we need the Russian program to make the official announcement," Priscu told National Geographic News via email.

Scientists have been drilling this shaft toward Lake Vostok—one of the world's largest freshwater lakes—since the lake was discovered in 1996. This field season, the Russian team has been drilling since the beginning of January.

As of February 6, the team was within 16 to 32 feet (5 to 10 meters) of reaching the under-ice lake, Priscu told BBC News.

With the Antarctic summer rapidly coming to a close, it's now or next year for the scientists, who are hoping to probe the Great Lake-size water body for the first time in 25 million years.

Once it happens, "it'll be a big splash, and I mean that metaphorically," Texas A&M's Kennicutt said.

Race to the Lake

Lake Vostok is the largest of more than 145 subglacial lakes—most of them several kilometers long—that have been discovered under the Antarctic ice in past decades.

These subglacial lakes may open a new window onto our planet, for example by offering new insights into climate history or revealing unknown life-forms.

Regardless of what they find, if the Russian team succeeds, "their efforts will transform the way we do science in Antarctica and provide us with an entirely new view of what exists under the vast Antarctic ice sheet," Priscu said Monday.

The water bodies' discoveries have also prompted a "race to the lakes"—similar to the early 20th-century race to the South Pole—from various research teams vying to be the first to penetrate a subglacial lake, Texas A&M's Kennicutt said.

The British, for example, plan to drill into another Antarctic lake, Lake Ellsworth, in the 2012-13 summer season, he said.

The Russian effort has been slowed by efforts to insure the drilling won't contaminate the lake water. The team, for example, was to use a hot-water drill during the last few meters to prevent any foreign material from entering the lake environment, Kennicutt said.

Reaching Lake Vostok "has become more than a scientific question—this is the centerpiece of the Russian Antarctic program," Kennicutt said.

"There's national pride, and the first-entry moniker is very important nationally to the Russians."